/robowaifu/ - DIY Robot Wives

Advancing robotics to a point where anime catgrill meidos in tiny miniskirts are a reality

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R&D General Robowaifu Technician 09/10/2019 (Tue) 06:58:26 No.83
This is a thread to discuss smaller waifu building problems, solutions, proposals and questions that don't warrant a thread. Keep it technical. I'll start.

Liquid battery and cooling in one
Having a single "artificial blood" system for liquid cooling and power storage would eliminate the need for a vulnerable solid state battery, eliminate the need for a separate cooling system, and solve the problem of extending those systems to extremities.
I have heard of flow batteries, you'd just need to use a pair of liquids that's safe enough and not too sensitive to changes in temperature.
This one looks like it fits the bill. The downside is that your waifu would essentially be running on herbicide. (though from what I gather, it's in soluble salt form and thus less dangerous than the usual variety)

How close are we to creating artificial muscles? And what's the second best option?
Muscles are perfect at what they do; they're powerful, compact, efficient, they carry their own weight, they aren't dependent on remote parts of the system, they can be controlled precisely, and they can perform many roles depending on their layout alone.
We could grow actual organic muscles for this purpose already but that's just fucking gross, and you'd need a lot of extra bloat to maintain them.
What we need are strands of whatever that can contract using electrical energy. Piezo does the trick at small scales, but would it be enough to match the real thing? There have been attempts, but nothing concrete so far.
What are some examples of technology that one could currently use instead?

High level and low level intelligence emulation
I've noticed a pattern in programs that emulate other computing hardware.
The first emulators that do the job at acceptable speeds are always the ones that use hacks and shortcuts to get the job done.
It comes down to a tradeoff. Analyzing and recompiling or reinterpreting the code itself on a more abstract level will introduce errors, but it is a magnitude of order more efficient than simulating every part of the circuitry down to each cycle. This is why a relatively high level emulator of a 6th gen video game console has close system requirements to a cycle-accurate emulator of the SNES.
Now, I want to present an analogy here. If training neural networks for every damn thing and trying to blindly replicate an organic system is akin to accurately emulating every logic gate in a circuit, what are some shortcuts we could take?
It is commonly repeated that a human brain has immense computing power, but this assumption is based just on the amount of neurons observed, and it's likely that most of them probably have nothing to do with intelligence or consciousness. If we trim those, the estimated computing power would drop to a more reasonable level. In addition, our computers just aren't built for doing things like neural systems do. They're better at some things, and worse at others. If we can do something in a digital way instead of trying to simulate an analog circuit doing the same thing, that's more computing power that we could save, possibly bridging the gap way earlier than we expected to.
The most obvious way to handle this would be doing as many mundane processing and hardware control tasks as possible in an optimized, digital way, and then using a GPU or another kind of circuit altogether to handle the magical "frontal lobe" part, so to speak.
Wear and maintenance
What would you do if your wife accidentally cuts her skin, or rubs it away? You could partition the skin into replaceable "plates", but it would be nice to have a substance that you could just paint over the damage with and let it dry, at least for smaller scratches. It could also be used to cover up the seams.
What about internals? You might have to replace the inner lining of the mouth and uh, other human interface cavities once in a while. I don't have any ideas for those yet, perhaps something that binds when exposed to water, as opposed to the skin thing which would do better if it reacted to air.
How do you refill liquids? Using water-soluble chemicals only for everything would be ideal, because replacing, filtering and removing excess water is quite trivial. Self-cleaning is important as well, that's another use for water.
An additional port for providing the raw chemicals for dissolving might be necessary. I would place it at the navel or at the tailbone. If it was the latter, it might function as an extension and charging port as well. Wouldn't it be nice to have a detachable tail containing an antenna or additional interfaces?

When liquids are involved in any capacity, you must consider the possibility of nasty things growing in said liquid (microbes, mold). Especially the ones that'll inevitably hop over from your own filthy monkey hide. Adding some biocide to fluids might be necessary, though that may be harmful to the user as well. You need to be very careful with it.
Other things that could help are; an internal temperature that's unfriendly to microorganisms (like a permanent fever, which might also feel quite pleasant to the user), and frequent removal of old fluids. If the water in circulation acts as a coolant (see first post), we wouldn't even have to go out of our way to heat it up. Your own PC's processors easily reach temperatures needed to sterilize any liquid.
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So I've been thinking of ways to manufacture cheap hydraulic muscles since weak pneumatic ones cost almost $100 for only 40 lbs of force. What a joke! But the answer seems simple: just make the woven sleeves out of strong nylon fishing line. Would it work?

Obviously making them by hand will be a ton of work just to make one sleeve, but once an initial prototype is tested and it works well then a 3D printable machine could be built to automate weaving fishing line into sleeves. The strength of fishing line is tremendous and it's cheap to buy. I estimate it would be able to withstand pressures up to 3500 psi, generating up to 2000 N of force. It'd be an open-source solution for powering our waifubots to give the Chinese merchants the middle finger.

A silent hydraulic system could also be built with quiet actuators for low cost rather than using a noisy pump. The only issue I see with this is that hydraulics can get extremely hot, up to 82°C before the system starts to breakdown. This heat could be dissipated though via a large heatsink on a thermoelectric generator using a diaphragm and artificial lungs. Our robowaifus would be able to exhaust excess heat by breathing and panting.

Some videos on hydraulic muscles:
Interesting idea about weaving together nylon fishing line anon, good thinking! Seems obvious now but I admit I hadn't thought of it yet. Maybe we can find some good manufacturing designs or tech, that can be used to both weave and twist the strands simultaneously? That might be a good electrically-driven muscle approach.

>A silent hydraulic system could also be built
While very desirable, I'm not sure how that would work exactly. Can you elaborate? Also, have improvements in hydraulics happened yet to make it more amenable to use inside a robowaifu? You know, the toxicity and maintenance hassle? It would be great if it becomes practical and cheap enough some day.

>Our robowaifus would be able to exhaust excess heat by breathing and panting.
I honestly wouldn't even mind her having strategically-placed vents like in:
and following.
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Vegetable oil can be used as hydraulic fluid. What makes artificial muscles different from the hydraulics of heavy machinery is that you don't have to pump a lot of fluid around or have a huge reservoir. The muscle can remain mostly full. It's the pressure that contracts it.

At 3500 psi hydraulic fluid is compressed by 0.5% so you only need to pump a tiny bit of fluid into the muscle at that pressure to get a maximum contraction. Sunflower oil apparently has even lower compressibility than hydraulic fluid, which should make it more efficient with less energy being lost as heat.

From looking around at experimental results it seems larger muscles use much less pressure but more fluid to exert the same force. Tiny muscles exerting 2 kN of force is pretty cool but I don't think anyone is going to wanna be near their robowaifu when a hose bursts at 3500 psi. We'll have to go without battle waifus and use larger muscles with safe psi levels.

How would we even get enough power for robowaifus to lift heavy objects? Join an array of 40V chainsaw batteries in parallel?
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That's great news about sunflower oil anon, thanks. I had no idea. I'll mark the toxicity issue off the list then. :^)

We'll still need reservoirs, fittings, valves and pumps that are both inexpensive and can take the literal pressure. Maybe further developments in materials will be available to us.

As far as delivering bursts of high current, it will be a challenge needing a solution regardless whether we go with hydraulics, electrical, or some type of hybrid. I think atp we have to assume she will be spending lots of time sitting in her 'recharging chair' at least for the first few versions.

The heat dissipation is probably a bigger Systems Engineering component challenge than any of us fully realize yet; what with all the energy being stored, transformed, and moved around and everything.

Makes me sit in awe again at the wonder of God's designs for biology tbh. It all just works so remarkably well together.
I think atp we have to assume she will be spending lots of time sitting in her 'recharging chair'
There can be swappable battery packs, air tanks or my favorite option at the moment have it connected directly to a power source.

The low power density of energy storage combined with high cost and complexity makes an autonomous design impractical at the moment. I envision 2 tubes being plugged into mine; one for hot water to circulate under the silicon skin covering and one for air to power the pneumatics. That way I can keep it in my bed as a giant warm body pillow even when it's turned off then plug in an air hose when I want it to move.
Fair enough. ATP you may be right. Certainly most of the low-budget lab work seen in videos has the robot tethered to external equipment.
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First attempt at winding fishing line into a sleeve for artificial muscle. This was a lot easier to do than I thought it'd be. I just stuck two pins into a piece of doweling and wrapped one piece of fishing line around back and forth in different directions crisscrossing it.

I need to figure out a way to keep the ends clean so it wraps even and a way to melt the ends together without burning the plastic. A machine could definitely do this better and faster than a person. I'm not sure how I'm gonna put attachments on the ends yet. I'll have to buy some parts for that but I'm pretty sure we'll be able to manufacture all the cheap artificial muscle we need.
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There is a machine you can make for automatic winding if you have access to a 3d printer;
Also are you using UHMWPE fishing wire? That's what the 3d printing community used before switching to belts.
Well that saves a fuckton of work. Thanks for the link. The only trick is it has to be a woven into a sleeve like a Chinese finger trap. I have to figure out a way to wind multiple lines at a time without messing them up.

And it's just some cheap 30-lbs nylon fishing line I had lying around. Nylon should be able to hold up to 3000 psi but I'm only going to be operating the muscles up to 80-100 psi.

I've been doing some reading on different materials and UHMWPE is stronger but it stretches twice as much as nylon which is no good for hydraulics. Kevlar has extreme resistance to stretching (50x more than nylon) and 100-lb Kevlar thread is only about 3x more expensive than fishing line. We'll have to experiment and see what works best.
>UHMWPE is stronger but it stretches twice as much as nylon
That depends if you're using high quality heat treated spun fiber or cheap monofilament extruded wire. I haven't done too much research into this field but the reprap community usually goes with specific materials for good reasons and it's been replacing kevlar fibers in body armor for years now.

>I have to figure out a way to wind multiple lines at a time without messing them up.
You could add a looming mechanism with several spools. That machine wasn't intended to make sheaths for hydraulic muscles but it'll do the job with some alterations. This thing is the best I could find on thingiverse for weaving.
Neat, thanks anon. I've been wondering if there were some DIY designs out there already for this problem of sleeve and other 'fabric' weaving. We'll have 101 needs in a full-featured robowaifu design for these things.
>This thing is the best I could find on thingiverse for weaving.
Not that anon, but very cool. Thanks.
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I just realized I have to weave all the lines in one pass. The lines are suppose to pass under, over, and under again.

A machine that manufactures braided tubing:

Inkle looming our own belts will save a lot of money.

TIT used kevlar braided tubing for their muscles but it costs a fortune to buy it.
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Got no clue what I'm doing but it's gotta be something like this.
Help newfags out with the lingo?
The inkle loom linked is a type of loom for making belts, bands and bracelets. TIT is the Tokyo Institute of Technology.
Got it thanks. Sorry to be nuisance, but if it's for robowaifus then it's interesting and I want to understand it better. How can this loom help robowaifus anon?
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Lapis anon here, I used tablet weaving last year to make /miku/ themed belts so I know how to tablet weave now (at least in a way, there are many ways to do it)

This thing looks like a holder stand, it simply makes weaving by hand easier, but it doesn't weave for you so its not a "machine"
I can also confirm the bulletproof 3dprints, but its a fairly recent thing; https://interestingengineering.com/researchers-3d-print-bulletproof-plastic-layered-cubes

Weaving is more work than I thought and it also costs in materials, but its nice for making custom things from one's own designs

I guess this is something like what you guys are working on; https://advances.sciencemag.org/content/3/1/e1600327
There are many ways to make woven muscles
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You can place motors inside limbs or other places and use a belt to transfer the mechanical energy to joints. Cocona Kosaka has belts to drive her joints so she doesn't need large heavy motors in them.

Parts are expensive, especially to get custom sized, so we're trying to manufacture as much as we can on our own.
OK, that makes sense. Can something like a timing belt for a car engine be used? Just trying to spitball here since I don't understand weaving very well but know cars a little.
Yeah, timing belts are most efficient. They're mostly used for shoulders, elbows and knees. You can buy them but you'll have to design around the length and size available. It's not uncommon to use wires. No one here really knows what's the best approach yet.
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This diagram shows how hydraulic muscles work. The weave contracts the bladder when air or fluid is pumped in.

It might be possible to buy double-end style towing sock cables made of the material you want rather than making your own.

Not so sure about the efficiency of belts compared to a synchromesh drive systems for use in robotics. Asides from taking up less space they can move in all directions, they're used in higher end 3d printers because the tension doesn't need to be adjusted which means better reliability in prints.
OK, thanks for the information anons. I understand it a little better now.
>synchromesh drive systems for use in robotics
I assume you mean something like this. I've never heard of it before.
I'm assuming that when the sleeve balloons is when force is being exerted into the armature to change it's shape?
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It's all ogre, bros. How will I look my robowaifu in the eyes when she realizes she has origami muscles because I'm too much of a brainlet?
Why are you all trying to make the sleeving? Why not just use something like this:

Although I think with this you'd probably rather have the silicone coating on the inside but as long as you don't cut them too long it wouldn't be hard to invert.
Barring that buy some expandable sleeving and run an inflatable tube through it.

Although truthfully as fun as the artificial muscle stuff is I think it's mostly a dead end outside of perhaps some "extra" features. Since it's so complex to control.
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Think of it as a finger trap, when pushed from the inside by air pressure the ends contract towards each other.

The type of weave it uses may be unsuitable or it won't contract much when the tube is filled under pressure and that thick silicone rubber might require a lot of pressure. We won't know until some tests are done.

I've also looked at some braided tubing and the smallest I've found is for model making, not sure what the outer sheath is made of or if the weave/vinyl tubing it uses would work.
>buy some expandable sleeving and run an inflatable tube through it.
That's an interesting idea. But I imagine that basically it'd be comparable in price and also far less of a pain to just buy it already pre-composited together. Still, inventive thinking anon.
Very nice hobby outlet anon, thanks for the link.
Found an interesting web page on the reprap forums that has a guide for making air muscles. There are other pages on robotic topics there as well.

>When the internal bladder is pressurized it expands and pushes against the inside of braided mesh sleeve, forcing the diameter of the braided mesh to expand. The physical characteristic of the mesh sleeve is that it contracts in proportion to the degree its diameter is forced to increase. This produces the contractive force of the air muscle.
So the type of weave on the braided mesh doesn't seem to matter? This other research paper on the topic brings up more questions so I probably won't get a good idea until tests are done first hand.

Another site on this topic with an interesting solution to combat wear;
>A significant improvement to these devices has been made by the Festo Corporation, which has recently introduced a new product called fluidic muscle. This operates on the same principles as a standard BPA, with the critical difference being that the fiber mesh is impregnated inside the expandable bladder. The resulting actuators have a demonstrated fatigue life on the order of 10,000,000 cycles at high pressure.
Thanks for that imagesco air muscle article anon, it's a very simple and useful approach. I made an archive of all the article pages to preserve it from disappearing on us. Grab it if you care to.
There was already a pdf of it but I didn't post it as the web page has links at the end which might be useful for research and there are other topics on the site. It's air-muscle-information-sheet-am-02l.pdf

And instead of sleeping I've been looking into the braided sheath question. Seems that asides for the angle being important there's no good way to model the behavior accurately for simulations Modelling_of_the_McKibben_artificial_muscle.pdf also pleated braided sheaths that can increase the contraction force seem much more difficult to manufacture but some very good ideas are presented in the thirdgenPPAM.pdf

And lastly there's frobt-05-00136.pdf which claims to have typical air muscles beaten on almost all fronts by using an origami folding approach.
Thanks anon. Please always dump any pertinent docs you may have here. Hopefully /robowaifu/ can become a clearing-house of sorts both for ourselves and for others in the future. I'm doing everything I know how to do to ensure we keep everything preserved in the event of future takedowns or other disruptions.

Question: I read in the promo article from the Pisa group that the angle of the weave was somehow variable. At least they implied it could control stiffness if adjusted. One thing they didn't make clear however if that was something that can be controlled dynamically, or if it has to be designed and placed into the material at manufacturing. Got any insights there?
Hey Lapis Anon, there's a post about wires that themselves contract when heated. Thought I'd try to catch you here about it.

Also, I hope you can tell us more about how weaving can be used for constructing robowaifus. Not for the attire and such, but for the mechatronics etc.
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>And lastly there's frobt-05-00136.pdf which claims to have typical air muscles beaten on almost all fronts by using an origami folding approach.
900% seems indeed to blow away all the competition. I wonder how many Newtons force you could manage with say a 12cm^2 paper face on the end of one of these types of effectors?
The fishing line was too hard to work with but I think I understand the winding pattern now. I'm gonna order a 3D printer soon and prototype a mechanism for winding mesh sleeves in various materials.

Tubing is expensive and meshes are usually woven in a way to prevent stretching and swelling. I'm more interested in trying new ideas that haven't been done yet with hydraulic artificial muscles. Most of the research has only been done on pneumatic ones or stress testing high-pressure hydraulic ones. I want to find a silent and powerful actuation system that can move like a human being.

The amount of strips or threads in the mesh affects the contraction length, less generally increases the contraction ratio. Bladder diameter and mesh diameter also affect the contraction length, smaller diameters have higher contraction ratios.
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>I wonder how many Newtons force you could manage with say a 12cm^2 paper face on the end of one of these types of effectors?
Found something on p7. It's actually quite powerful tbh.
>I'm gonna order a 3D printer soon
Always a big deal. Any idea what you're going to get anon?

>I want to find a silent and powerful actuation system that can move like a human being.
Godspeed Anon.
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>dat mp4
heh poor choice of words. archival library is probably a better choice. :^)
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>One thing they didn't make clear however if that was something that can be controlled dynamically, or if it has to be designed and placed into the material at manufacturing.

There's a movable fitting at the bottom of the diagram and they mention that the user can change the initial braid fiber angle independently. Since they're only doing basic tests they probably changed it by hand between setups but adding in a mechanism to change it dynamically seems the logical next step.

The most interesting thing about this is the rotational possibilities when using them in parallel.

Here's another paper on those origami shaped air muscles. More powerful and compact when compressed yes but they're not ideal for larger muscles on humanoid robots because of the large volume they take up.

For anyone having trouble getting access to research papers there's libgen.is that has almost everything when it comes to scientific articles.
Thanks, I'll read it.

>large volume
Hmm. I wonder if they would serve inside the thorax and possibly inside the thighs then? They do seem to be able to bring a remarkable amount of force to bear given their quite light weight.

>For anyone having trouble getting access to research papers there's libgen.is that has almost everything when it comes to scientific articles.
Thanks for finding them and posting them here for us to read Anon, much appreciated. :^)
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>because of the large volume they take up.
Obviously, alternative designs can be managed tbh.
What if you bundled long strips packaging up many of these things together and then activated them all simultaneously? Wouldn't that somewhat mimic the way actual muscle tissues in both structure and behavior?
I'd prefer weaves over heating, I've seen memory metal before and its interesting, but I'm not sure if actuators are the proper application of it
I've been kinda out of it for a while, but I think using fishing line may be a good idea
>I'd prefer weaves
>I think using fishing line may be a good idea
I'm assuming you'd want to weave fishing line as an actuator then? I think the anon who's buying a new 3D printer ITT is taking the same approach.
That will be interesting to watch develop as a technology, thanks.
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An Anycubic Mega-S
>The type of weave it uses may be unsuitable or it won't contract much
Behaves pretty well as far as I remember but I haven't tried this particular one.
Regardless short of buying the pneumatic muscle from Festo the wire sleeving is the cheapest and most effective bet. I've had good luck in the few times I've made pneumatic muscles in the past with it.

That said I still think a cable driven design is the better route to explore. I'm going to be doing some experiments in that direction after the holidays.
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klann linkages are really fun. Would make for a nice robo monmusume base.
Great. I hope you let us know how the assembly & operation of this printer goes anon.

Kek, that's awesome. Did you do this yourself anon?
>klann linkages

they won't be doing bipedal robots anytime soon by the look of it, but interesting. maybe an all-terrain walker for you and your robowaifu to ride around in?
Jansen's Linkage seems like an interesting mechanism too. I could kind of re-visualize this as a sort of quadruped animal shoulder. If you extended the lower 'leg' and added a movable paw on the end you'd be set. The motive impulse seems to be a single rotary mechanism and one fixed pivot point.
it just occurred to me while watching this mesmerically that if you added a movable coupling at the pivot point that you could slide along an arc-shaped grove on demand, then you could create a synchronized motion that could rhythmically impart more force down at the end effector (by multiplying it's horizontal offset). This sliding motion at the coupling can also likely be tied directly to the rotary impulse using additional linkage.

The intended effect would be kind of like the way a greyhound dog can really 'lean into it' while chasing a rabbit.
I wonder it there is some way to adapt this to a bipedal robowaifu?
Long time ago as a side project.

Yeah dynamics aren't the best on it. The site you link has some better walking linkages. You can see why in that video too klann linkages have a halting sort of gait as they don't have a very steady velocity curve. It does give a neat crab like effect though if that's what you're going for.
I want to make a snibbedy snab one at some point. Maybe I'll try out that trot bot linkage.

Jansen linkage looks pretty but it doesn't have real great mechanics. If you only use it on flat ground it could be okay but they require 3 for a steady gait vs 2 for other walking linkages.
>I want to make a snibbedy snab one at some point. Maybe I'll try out that trot bot linkage.
That would be cool. Good luck.
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>>1805 Give your waifu a tail, if you're ok with her chunky legs, you're golden. Hope you like short stacks anon. Friendly reminder that cable based drives are smaller, lighter, more durable, and most importantly, far more efficient then pneumatic systems. I actually really like pneumatic systems, I've worked on/with and designed pneumatic systems in the past. You can find industrial spares on ebay or in junk yards that usually work ok or need basic maintenance if you'd like to use them for manufacturing mechanisms. They are phenomenal as parts for industry, but their relatively low efficiency and high mass (compared to cable mechanisms driven by brushless motors) prevents them from being usable for waifus at or below standard human heights. Theoretically viable for giant waifus above 8 feet tall as the torque required to move increases drastically. Pnuematics only really make sense on stationary robots. Which is why they're used in amusement parks where a giant compressor can power many animatronics that only worry about the mass of their upper bodies.
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Extremely useful free software for waifu mechanical development. https://blog.rectorsquid.com/download-linkage/
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>>1879 A design for a leg which runs with only one motor. It's simple, easy to implement into a design, somewhat efficient, and with an extra motor in the hip, can be used for walking, running, sitting, standing, all based on the angle of the mechanism. It's lacking a foot though, if anyone would like to help with that. (not sure how to include a copy of its file, julay doesn't support the file type.)
>>1692 Make sure you look at the elastic stiffness of the material, also known as the modulus of elasticity or Young's modulus. Not the total stretch at breaking point. Plastics often plastically deform greatly before breaking so looking at the total elongation does not give a good idea of stiffness. Same with metals. Mostly people design things to stay in the elastic limit. Im saying this because I'm pretty sure that UHMWPE is stiffer than nylon.


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